In Paragraphs 1-4 and 1-6 the difference between heat and temperature was explained.
A thermometer may be used to measure temperature. Heat must be calculated. There is no instrument for measuring the amount of heat in an object.
The unit of heat is the British thermal unit (Btu). A Btu is defined as the amount of heat required to raise the temperature of 1 pound of water, 1 degree Fahrenheit, as shown in Fig. 1-14.
Conversely, if a substance is cooled, heat (Btu's) is removed.
Example: How much heat will be required to raise the temperature of 62.4 lbs.
(1 Cu. ft.) of water from 40 F. to 80 F.?
Btu = Wt. x degree change
= 62.4 x 40
= 2496 Btu
Example: How much heat must be removed to cool 50 lbs. of water from 80 F. to 35 F.?
Btu = Wt. x degree change
= 50 x 45
= 2250 Btu
Tags:
Basics of Refrigeration